1. Technical Field
The present application relates to a swimming pool, spa, or combination swimming pool and spa, heated with a heat pump with a heat exchanger.
2. Background Information
Swimming and relaxing in a pool or spa are extremely popular pastimes in the United States. Swimming pools, both public and private, offer people relief from the heat while also offering an opportunity for social gatherings and fun for adults and children. Several types of swimming pools and spas exist, including in-ground pools, above-ground pools, wading pools for small children, spas, hot tubs, and whirlpools. Swimming pools and spas can be located outdoors, as in the back yard of a person's house or at a public community pool, or indoors, as in at a hotel pool or a private indoor pool. Further, swimming pools can be found in all different sizes, ranging from a small, above-ground pool that is only a few feet in depth, to a large, Olympic-sized pool, designed for competitive swimming or diving. Spas, hot tubs, and whirlpools can also be found in different sizes.
Many pools, especially indoor pools, are typically heated for the comfort of swimmers. Spas, hot tubs, and whirlpools are also heated for the comfort of users, as well as for therapeutic purposes for users. Since most indoor pools, including hotel pools and community pools, remain open to users year-round, and since most spas also remain open year-round, it is necessary for the heat exchanger to be able to constantly work with as little maintenance or repairs as possible.
Due to the necessity of swimming pool pumps to move or turn over the entire volume of pool water through the pool filter several times a day, any full flow heat exchanger must handle a high flow rate and thus high velocity of the water flowing through the heat exchanger. This high velocity poses several problems, as the high velocity could cause vibration of the coils which naturally have a spring resonant frequency and are prone to vibration. The vibration could be in the hundreds or even thousands of cycles per second, and over a short amount of time, the vibrations could rub a hole in the wall of the thin heat exchanger tube if the wall of the thin heat exchanger tube is allowed to contact either the adjacent tube wraps or the outer shell.
Due to the corrosive chlorine and pool sanitation chemicals used to treat swimming pools, including inorganic chlorinating agents such as calcium hypochlorite, lithium hypochlorite, sodium hypochlorite, and organic chlorinating agents such as trichloroisocyanuric acid, potassium dichloroisocyanurate, or sodium dichlorocyanurate as anhydrous or dihydrate forms, the tube material may comprise an alloy such as titanium or any high alloy stainless steels that can withstand these chemicals without fouling or corrosion, and to ensure continued service over time. The above alloys are typically costly materials, and thus to maximize heat transfer and to minimize expense, very thin wall tubing is commonly used in swimming pool and spa heat exchangers. Alloys such as these develop a hard film oxide coating, which helps to prevent the corrosion caused by chlorine and other pool sanitation chemicals. Because of this very abrasive coating, extra care must be taken to prevent tube damage caused by the wall tubing rubbing together if the wall tubing is allowed to touch and vibrate.
In addition, the tube wraps must be centered for optimum heat transfer uniform velocity. Therefore, a method and device for holding the tube wraps apart and centering the tube wraps would be beneficial to minimize damage and promote optimal operation.
Various methods of holding tube wraps apart and centering tube wraps have been used, including injecting silicone rubber between the tubes at intervals to freeze them in place, spreading the wraps apart and inserting rubber or plastic bumpers between the tubes, or placing long strips of material axially between the inner and outer coils during or after they are formed. All of these methods, however, have the disadvantage of requiring substantial care and time to assemble, and, in some cases, baking or curing time to set up the material before the heat exchanger coils can be used. Further, many of these methods are also costly to manufacture.